Experimental and computational studies of silver(I) dibenzoylmethane-based complexes, interaction with DNA/RNA/BSA biomolecules, and in vitro cytotoxic activity

Two silver(I) complexes of composition [Ag₂(L)₂] (1) and [Ag(L)(PPh₃)₂](2) (HL = dibenzoyl- methane, PPh₃ = triphenylphosphine) were synthesized and characterized by elemental analysis, FTIR, NMR, XRPD, and UV-visible spectra. The molecular structures of the studied ligands and Ag(I) complexes have been characterized using Density Function Theory (DFT) calculations. This analysis has enabled us to determine the reactivity and the coordination site(s) for each ligand. Ag(I) ion is found to be coordinated with the ligand's oxygens in almost a linear fashion in complex (1), while in complex (2) it adopts a tetrahedral geometry. The interaction compounds with biomolecules; calf thymus (ct DNA), yeast-tRNA, and bovine serum albumin (BSA) were investigated using both absorption and fluorescence spectroscopy. The in vitro cytotoxic studies of the complexes against normal human lung fibroblast (WI38), cancerous breast (MDA-MB-231), mammary gland breast (MCF7), hepatocellular (HePG2), and prostate (PC3) cell lines indicated that the complexes are highly toxic to the cancer cells but less toxic towards the normal one when compared with the ligand. Flow cytometric results showed that complex (1) induced cell cycle arrest at the G2/M phase, and complex (2) at G2/M and S phases. Moreover, the results of apoptotic genes (caspase3 and p53) and anti-apoptotic (Bcl2) led us to suggest an apoptotic killing mechanism of cells rather than a necrotic one.

AgX-based hybrid coordination polymers: mechanochemical synthesis, structure and luminescence property characterization

Hybrid coordination polymers are interesting for their ability to converge the properties of both inorganic and organic systems in one single compound and recently attention has been focused on silver based hybrid coordination polymers due to their luminescence properties. We searched the CSD to establish the propensity of AgXL (X = Cl^-, Br^- and I^-) with L as an organic ligand to form hybrid coordination polymers. About 800 AgXL structures are deposited in the CSD, with huge structural variability: indeed, it is possible to recognize some structural preferences based on the halide nature. The formation of an inorganic polymeric unit is favoured by iodide but it is also possible with the other halides. This research continues with the synthesis of AgX (X = I^-, Br^-) based coordination polymers with 2-, 3- and 4-picolylamine (n-pica) as ligands. By mechanochemical synthesis five new hybrid coordination polymers and one coordination polymer have been obtained and their structures determined. While [(AgI)(n-pica)]_n are not luminescent, [(AgBr)(n-pica)]_n emit and their profile depends on the crystallinity of the sample.

Mechanism and principle of doping: realizing of silver incorporation in CdS thin film via doping concentration effect

A high-quality buffer layer serves as one of the most significant issues that influences the efficiency of solar cells. Doping in semiconductors is an important strategy that can be used to control the reaction growth. In this study, the influence of Ag doping on the morphological, optical and electrical properties of CdS thin films have been obtained. Herein, we propose the mechanism of CdS film formation with and without Ag ions, and we found that changes in the reaction of preparing CdS by the chemical bath deposition (CBD) method cause a shift in the geometric composition of the CdS film. XRD showed that the position of peaks in the doped films are displaced to wider angles, indicating a drop in the crystal lattice constant. The optical analysis confirmed direct transition with an optical energy gap between 2.10 and 2.43 eV. The morphological studies show conglomerates with inhomogeneously distributed spherical grains with an increase of the Ag ratio. The electrical data revealed that the annealed Ag-doped CdS with 5% Ag has the highest carrier concentration (3.28 × 10¹⁵ cm^-3) and the lowest resistivity (45.2 Ω cm). According to the results, the optimal Ag ratio was obtained at Ag 5%, which encourages the usage of CdS in this ratio as an efficient buffer layer on photovoltaic devices.

An in-depth analysis of nucleation and growth mechanism of CdS thin film synthesized by chemical bath deposition (CBD) technique

The aim of this study is to acquire a deeper understanding of the response mechanism that is associated with the formation of CdS thin films. We presented an effective and new hybrid sensitisation technique, which involved the 1-step linker between the related chemical bath deposition (CBD) process and the traditional doping method during CBD for synthesising high-quality, CdS thin films. The mechanism for the combined synthesis of the films is also describes. CdS films were electrostatically bonded to soda-lime glass, causing the formation of the intermediate complexes [Cd(NH₃)₄]²⁺, which aided in the collision of these complexes with a soda-lime glass slide. In the one-step fabrication technique, 3-Mercaptopropionic Acid (MPA) was employed as a second source of sulphur ions and a linker molecule. Optical studies showed that the bandgap ranged between (2.26–2.52) eV. CdS + MPA films exhibited a uniform distribution of spherical molecules based on their morphological properties. After annealing, this approach significantly altered the electrical characteristics of CdS films. The CdS + MPA films displayed the highest carrier concentration whereas the CdS + Ag + MPA films exhibited the lowest resistivity, with a jump of 3 orders of magnitude.

Conformational Adaptation of β-Peptide Foldamers for the Formation of Metal-Peptide Frameworks

Metal-coordinated frameworks derived from small peptidic ligands have received much attention thanks to peptides' vast structural and functional diversity. Various peptides with partial conformational preferences have been used to build metal-peptide frameworks, however, the use of conformationally constrained β-peptide foldamers has not been explored yet. Herein we report the first metal-coordination-mediated assembly of β-peptide foldamers with 12-helical folding propensity. The coordination of Ag⁺ to the terminal pyridyl moieties afforded a set of metal-peptide frameworks with unique entangled topologies. Interestingly, formation of the network structures was accompanied by notable conformational distortions of the foldamer ligands. As the first demonstration of new metal-peptide frameworks built from modular β-peptide foldamers, we anticipate that this work will be an important benchmark for further structural evolution and mechanistic investigation.

Balancing connectivity with function in silver(i) networks of pyridyltriazole (tzpa) ligands results in the formation of a metallogel

A new flexible and divergent 1,2,3-triazol-4-yl-picolinamide (tzpa) ligand 2 and the half-equivalent model ligand 1, both functionalised with pendant 3-pyridyl groups, are reported and their coordination behaviour with silver(i) ions is explored, both in the crystalline phase and through the formation of a supramolecular metallogel. The self-assembly of tzpa ligand 1 with AgCF3SO3 resulted in the formation of a 1D coordination polymer, binding in a bidentate fashion through the pyridyl and triazole nitrogen atoms of the tzpa binding site and a pendant pyridyl nitrogen atom of an adjacent ligand. Doubling the number of metal binding sites in ligand 2, while retaining the same metal binding domain, gives rise to the formation of a supramolecular metallogel on reaction with AgBF4 at 5 wt% in MeCN, possessing self-healing properties.

Nine-Residue Peptide Self-Assembles in the Presence of Silver to Produce a Self-Healing, Cytocompatible, Antimicrobial Hydrogel

Silver compounds have been used extensively for wound healing because of their antimicrobial properties, but high concentrations of silver are toxic to mammalian cells. We designed a peptide that binds silver and releases only small amounts of this ion over time, therefore overcoming the problem of silver toxicity. Silver binding was achieved through incorporation of an unnatural amino acid, 3'-pyridyl alanine (3'-PyA), into the peptide sequence. Upon the addition of silver ions, the peptide adopts a beta-sheet secondary structure and self-assembles into a strong hydrogel as characterized by rheology, circular dichroism, and transmission electron microscopy. We show that the resulting hydrogel kills Escherichia coli and Staphylococcus aureus but is not toxic to fibroblasts and could be used for wound healing. The amount of Ag(I) released by hydrogels into the solution is less than 4% and this low amount of Ag(I) does not change in the pH range 6-8. These studies provide an initial indication for use of the designed hydrogel as injectable, antimicrobial wound dressing.

Pore space partition of a fragile Ag(i)-carboxylate framework via post-synthetic linker insertion

Pore space partitioning via post-synthetic insertion of dipyridyl linkers with different lengths modulates the porosity of Ag(i)-based MOFs.

Understanding the interplay between π–π and cation–π interactions in [janusene–Ag]+ host–guest systems: a computational approach

Guiding the development of new systems with increased cation–π interaction capability.

A stable 1D helical silver coordination polymer with red emission

Here, a new 1D helical chain coordination polymer with enhanced chemical stability and fluorescence emission was prepared by introducing a benzimidazole molecule into Ag₁₂ clusters.

Selective Analysis of Sulfur-Containing Species in a Heavy Crude Oil by Deuterium Labeling Reactions and Ultrahigh Resolution Mass Spectrometry

A heavy crude oil has been treated with deuterated alkylating reagents (CD₃I and C₂D₅I) and directly analyzed without any prior fractionation and chromatographic separation by high-field Orbitrap Fourier Transform Mass Spectrometry (FTMS) and Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR MS) using electrospray ionization (ESI). The reaction of a polycyclic aromatic sulfur heterocycles (PASHs) dibenzothiophene (DBT), in the presence of silver tetrafluoroborate (AgBF₄) with ethyl iodide (C₂H₅I) in anhydrous dichloroethane (DCE) was optimized as a sample reaction to study heavy crude oil mixtures, and the reaction yield was monitored and determined by proton nuclear magnetic resonance spectroscopy (¹H-NMR). The obtained conditions were then applied to a mixture of standard aromatic CH-, N-, O- and S-containing compounds and then a heavy crude oil, and only sulfur-containing compounds were selectively alkylated. The deuterium labeled alkylating reagents, iodomethane-d₃ (CD₃I) and iodoethane-d₅ (C₂D₅I), were employed to the alkylation of heavy crude oil to selectively differentiate the tagged sulfur species from the original crude oil.

Anion dependent silver(i) complexes of pyrazine mono-N-oxide

Pyrazine mono-N-oxide reacts with silver salts to form either discrete complexes involving monodentate N-coordination or 1D coordination polymers in which the ligand acts in a N,O-bridging bidentate coordination mode.